The Canon Mount Adapter EF-EOS M ($199.99 direct) is simple in concept: It makes it possible to use EF-S and EF Canon SLRs lenses on the company’s freshman entry into the compact interchangeable lens camera market, the EOS M. It has electronic contacts, so you can control lens aperture just as you would with a native lens, and supports autofocus.
Lens design dictates that, in order for a lens to properly focus to infinity, it must be a fixed distance from a camera’s image sensor. Because Canon SLRs are so much thicker than the EOS M, this means that the adapter essentially doubles the depth of the compact mirrorless camera. The adapter includes a removable tripod mount, which is helpful when using it in conjunction with heavier zoom or telephoto lenses and a monopod or tripod.
The EOS M isn’t quick to focus with native lenses, and it’s even slower to focus with adapted ones. I tested the adapter with the EF 28mm f/1.8 USM and the EOS M required about 1.9 seconds to focus and fire a shot with that lens in good light. The same lens focuses in about 0.25-second on the EOS 6D. Because the lens doesn’t have an STM focus motor, it stutters back and forth in short bursts as it attempts to lock focus for stills and video alike. You may be better off using adapted lenses in manual focus mode, especially for video. Thankfully the EOS M has a sharp rear LCD and you can easily magnify a portion of the Live View feed for more precise manual focus.
Sony offers a pair of similar adapters for its NEX camera system. The LA-EA1 is also priced at $200, and like the Canon adapter it relies on the NEX camera body’s focus system to work. There’s also a $400 LA-EA2, which features an integrated phase detect focus system. This delivers SLR-style focusing with adapted lenses. It’s a feature that would go a long way to improve SLR lens performance with the EOS M.
If you’ve already bought into the EOS M system, you’re used to its slow autofocus performance. This adapter works as advertised, but understand that performance with adapted SLR lenses will be slower. Considering that it doubles the depth of the EOS M, and that SLR lenses are bulky compared to a mirrorless camera to begin with, you may be better off simply skipping the adapter and simply carrying a D-SLR when you need a lens that isn’t available for the EOS M. But if you have a library of Canon SLR glass and are set on using it along with the EOS M, this accessory is a necessary one.
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